Computational Complexity Analysis of MPEG-4 Decoder

1. Computational Complexity Analysis of MPEG-4 Decoder Student : Chung-Yen Tsai Adivisor : Prof. David W. Lin Date : 2005/06/08

2. Outline • Corrections of The Computational Complexity in MPEG-4 Encoder(MoMuSys) • Analysis of Computational Complexity in MPEG-4 Decoder(MoMuSys) • Summary • Future Work • Reference

3. Outline • Corrections of The Computational Complexity in MPEG-4 Encoder(MoMuSys) • Analysis of Computational Complexity in MPEG-4 Decoder(MoMuSys) • Summary • Future Work • Reference

4. Profile of MoMuSys Encoder in Previous Group Meeting The information will be gathered in another unit. The Sum of Contribution is Not 100% The contribution of ME is not accurate

5. The Cause of The Fault Redundant Part for Framed-Based Coding Scheme.

6. Correction of The Profile ※Samples is the unit used in VTune Performance Analyzer (msec)

7. Correction of The Computational Complexity

8. Outline • Corrections of The Computational Complexity in MPEG-4 Encoder(MoMuSys) • Analysis of Computational Complexity in MPEG-4 Decoder(MoMuSys) • Summary • Future Work • Reference

9. Block Diagram of MPEG4 Decoder

10. Profile of The Original MoMuSys Decoder

11. Distribution of Execution Time (Cont’d) DecodeVopCombinedMotion ShapeTextureInterErrRes 54.9% DecodeVideoPacket CombinedInterErrRes 34.3% VopMotionCompensate 33.6% VopTextureUpdate 30.8% Decode Combined PacketInfo InterErrRes 98.9% fprintf 91.1% GetPred _Advanced 3.5% AllocImage 2.4% PrintOut MBData 93.9%

12. Distribution of Execution Time (Cont’d) DecodeVopCombinedMotion ShapeTextureInterErrRes 61.1% DecodeVideoPacket CombinedInterErrRes 68.5% VopMotionCompensate 15.6% VopTextureUpdate 9.0% Decode Combined PacketInfo InterErrRes 98.4% GetPred _Advanced 29.9% AllocImage 28.6% Interpolate Image 20.1% fprintf 15.5%

13. Distribution of Execution Time (Cont’d) – For Texture Decoding DecodeCombinedPacketInfoInterErrRes 98.9% GetMBblockdata NoDataPartErrRes 88.0% GetMBheaderNo DataPartInterErrRes 5.4% GetMBvectorsNo DataPartErrRes 3.6% PrintOut MBData 75.1% VlcGetBlock 16.1% BlockIDCT 3.6% Block DequantH263 0.4%

14. Distribution of Execution Time (Cont’d) – For Texture Decoding DecodeCombinedPacketInfoInterErrRes 98.4% GetMBblockdata NoDataPartErrRes 76.1% GetMBheaderNo DataPartInterErrRes 8.3% GetMBvectorsNo DataPartErrRes 7.1% PrintOut MBData 0% VlcGetBlock 69.3% BlockIDCT 15.3% Block DequantH263 5.9%

15. File_I/O and Non_File_I/O

16. Modification of MoMuSys Decoder • After removing PrintOutMBData, contribution of IDCT and VLC became larger. • There were also some files written to trace some information in “Debug” mode, and it is removable. • VopTextureUpdate is used to add the decoded texture on the M.C. image. Thus, fprintf is not removable here.

17. Profile in MoMuSys Decoder

18. Definition of DCT and IDCT in MPEG-4 Standard

19. The Theoretically Computatoinal Complexity • We use the 8X8 block based DCT and IDCT. • DCT:64(7_mult,4_div,2_cos),2_mult,1_div • IDCT 64(9_mult,4_div,2_cos),1_mult,1_div

20. Computational Complexity of Each Frame

21. Summary • In MoMuSys Encoder, Motion Estimation is the main contribution. The SAD calculation occupies most execution time. • However, the execution time of Motion Compensation and Texture Decoding is less than that of File I/O and Memory operations. • Since the VTune Performance Analyzer is run under Debug Mode, there will be some redundant executions, which increae Files I/O.

22. Future Work • Complete the analysis of Object-Based MoMuSys Codec. • Run some simple simulation on PAC simulator.

23. Reference • Standard of MPEG-4 (Text of ISO/IEC 14496-2:2001 (Unifying N2502, N3307, N3056, and N3664) )